Canadians Study Glyphosate-Resistant Ragweed

Following up their work from last spring which confirmed the first finding of a glyphosate-resistant weed in Canada, University of Guelph weed scientists have now confirmed the presence of additional glyphosate-resistant populations in soybean fields in southwestern Ontario.

Greenhouse testing of seed samples collected from southwestern Ontario in the fall of 2009 showed that an additional 16 fields had populations of giant ragweed (Ambrosia trifida) resistant to glyphosate. As part of the ongoing research conducted by Dr. Francois Tardif and Dr. Peter Sikkema from the department of Plant Agriculture at the University of Guelph, giant ragweed seed was collected from 57 fields across Essex, Kent and Lambton Counties in 2009 in an attempt to document the distribution of glyphosate-resistant giant ragweed in Ontario. Samples collected from the 41 other fields were found to be effectively controlled with glyphosate and therefore, were not found to be resistant. All resistant populations from this survey were located in Essex County in southwestern Ontario.